I have little spots on the inside on my mouth and a sort of rash on the roof and back of my mouth. I don't know what it is..?

I noticed an odd taste in my mouth last week but didn't think much of it. I was drinking a glass of lemonade and i couldn't taste a whole lot.

I looked in the mirror this morning and noticed little spots on my tongue and a sort of rash on the roof of my mouth.

I have no idea what it is but will be making a doctors appointment today.